Hi, everybody. I'd like to know how to refer to a "first love" when the "first love" is a girl. Is it still in the masculine form? I've tried searching to see if "la sua prima amore" is Italian but I got no results, but then I also found no examples of a boy talking about "il suo primo amore." All of the examples are girls talking about boys!

Context: writing about a character in a novel.
The protagonist is remembering a Christmas with his first love when he was fifteen years old.
Il protagonista ricorda un Natale con il suo primo amore quando aveva quindici anni.

(I don't want it to sound as if his first love was a boy. I appreciate your help.)